In many applications, a need exists to classify or detect a vehicle type. For example, an automated car wash or other paid service may need to confirm the type of vehicle being driven through the gate for billing purposes. As another example, an electronic toll way or traffic control system administered by a government may need to identify a vehicle for verification and charging purposes. As yet another example, an insurance company may create an opt-in service that allows the company to reliably determine which of several vehicles in a multi-vehicle household is being driven. In this latter example, the aggregate risk with respect to a family or household may be calculated based on the knowledge of which vehicle is being driven by which member of the household at a particular time. Thus, there exists a need to classify vehicles in an accurate manner.
In theory, it is possible to classify vehicles by analyzing sounds generated by those vehicles (e.g., sounds emitted by the vehicle engines). However, such techniques would likely be costly (e.g., if utilizing dedicated audio sensors within the engine compartment), and/or may give rise to privacy concerns (e.g., if utilizing audio sensors within the passenger cabin). With regard to privacy, the idea that private communications may be recorded and transferred over the Internet—even if the amount of captured communications is de minimis—is unacceptable to many consumers. Despite the best intentions of the creators of useful products and services, the possibility of inadvertent disclosure or recording of sensitive personal data may exist, especially if the data is transmitted and/or stored remotely. In general, therefore, the collection and/or storage of audio data reflecting private communications is a liability for service providers.